KR100317255B1 - Method for improving Channel-efficiency using Adaptive Time Slot - Google Patents

Abstract

In the LMDS system, in particular, in order to provide a multimedia service in the LMDS system, a method of improving channel efficiency using a structure of an uplink time slot in an adaptive time slot method is provided. And an uplink timeslot in transmitting data, a polling time slot in which the subscriber device sends a response when polling all the subscriber devices every predetermined time, and a signal through the polling time slot in the out of sync condition interferes with other timeslots. A protection time slot to prevent the system from becoming a service, a competition time slot in which the subscriber device sends control data to the headend device, a reservation time slot in which user data is sent, and an adaptive time slot consisting of a portion of the competition time slot and a portion of the reservation time slot. Wherein the adaptive timeslot is determined according to traffic conditions. The present invention relates to a method for improving channel efficiency using an adaptive timeslot method that can flexibly cope with rapidly changing traffic.

Description

Method for improving Channel-efficiency using Adaptive Time Slot}

The present invention relates to an LMDS system. In particular, the present invention relates to a method for improving channel efficiency using a structure of an uplink time slot in an adaptive time slot scheme when a multimedia service is to be provided in an LMDS system.

In general, due to the development of wireless communication technology and the development of the millimeter wave band, a broadband wireless subscriber network (B-WLL), which is advantageous in terms of ease of network construction, scalability, and economics, is in the spotlight.

In order to realize the broadband wireless subscriber network (B-WLL), Korea announced the frequency in the 20 GHz band, and similar systems include the Canada's Local Multipoint Communication System (LMCS) and the US Regional Multipoint. Distributed Services (LMDS) and ATM Wireless Access (AWA) in Japan are being studied.

Standardization in relation to broadband wireless subscriber networks (B-WLL) is most prominent in the work of the Digital Audio Visual Council (abbreviated as DAVIC).

DAVIC publishes the 1.0 specification up to the 1.3 specification and presents the only specific standard for the broadband wireless subscriber network (B-WLL). DAVIC mentions down time division multiplexing (TDM), up time division multiple access (TDMA) multiple access schemes, and downlink, uplink frame structure, and media access control protocol. have.

In Korea, Ministry of Information and Communication Announcement No. 1997-49 specifies the frequency for the subscriber line of the broadband wireless subscriber network (B-WLL), which allocates 2 하향 down from 25.5 ㎓ to 27.5 에서 for bidirectional broadband service in the 20 ㎓ band. Upwardly, 500 MHz of 24.25 Hz to 24.75 Hz was allocated. Of these, the 800 MHz band of 26.7 GHz to 27.5 GHz was temporarily designated for cable television (CATV) transmission.

As such, ultra-high-speed broadband multimedia service using subscriber line frequency in the millimeter wave band (2MHz downwards 25.5㎓-27.5㎓ and 500MHz upwards 24.25㎓24.75㎓) for subscribers within a radius of about 2-5km. An LMDS system that provides is a system developed to deliver multi-channel TV programs to subscribers as a competition for wirelines in the cable television market.

Initially mainly used for cable TV distribution, it gradually developed into a two-way digital system, and the services that a system of two-way high-speed wireless communication concept can provide include voice telephone service, data communication service, interactive video service, voice / data / There are multimedia services and dedicated line services that combine video, and have subscriber types such as general public network subscribers, private network subscribers, and public network transmission relays.

In addition, MMDS, a broadband wireless subscriber network that provides wireless cable television service or high-speed Internet service using subscriber line frequencies in the millimeter wave band (2.535 GHz to 2.655 GHz) for subscribers within a radius of about 30 to 50 km. Standards are also presented in the DAVIC 1.3 specification.

1 is a block diagram illustrating some components of an LMDS system.

Referring to FIG. 1, the LMDS system includes a central office unit (COU) 10, a head-end unit 20, and a hub outdoor unit (HOU). 30 and a Customer Premises Equipment Unit (CPE) 40.

The central office device (COU) 10 includes an ATM switching unit 11, a subscriber management system (SMS) 12, a network management system (NMS) 13, and a network. An interworking device (IWF) 14, a private switching device 15, and an Internet gateway 16.

The private exchange device 15 is interoperable with a PSTN for access to a public telecommunication network, and the Internet gateway 16 is an Internet service provider for an Internet service (ISP). Provides a connection with

The ATM switch 11 analyzes the data of the ATM cell structure used in the LMDS and performs switching to deliver the analyzed data to the subscriber.

In LMDS, TV broadcast data can be transmitted using an ATM cell, and digital data and voice data can be bidirectionally communicated. Thus, data used in an LMDS system is roughly classified into TV broadcast data, digital data, and voice data.

The subscriber management device (SMS) 12 is responsible for all operations, state management, and information management of the subscriber device (CPE) 40 through the information exchange with the ATM switching device (11).

The network management device (NMS) 13 is responsible for network connection and state management between the ATM switching device 11 and the hub outdoor device (HOU) 30 through an optical signal carrier (OC-3). And manages a wireless section state with the subscriber device (CPE) 40.

When the network interworking device (IWF) 14 exchanges data between the ATM switching device 11 and the private switching device 15, the ATM switching device 11 and the private switching device 15 interoperate with each other. For this purpose, the network interworking device (IWF) 14 is composed of hardware and software modules. Here, the data exchanged between the ATM switching device 11 and the private switching device 15 are generally text, image, and packet data.

The private exchange device 15 manages the charging information for the subscriber device (CPE) 40 when the LMDS is converted into a private network service and is available, and interoperates with the PSTN for communication.

The Internet gateway 16 is a gateway for providing ATM and local area network services (CLANs) to a subscriber device (CPE) 40. An Internet service providing Internet services for this purpose is provided. It is connected to the access network (ISP: Internet Service Provider).

The head-end unit 20 modulates down channel data of the ATM cell structure transferred from the ATM switching unit 11 and transmits the down-channel data to the hub outdoor unit (HOU) 30. The upstream channel data transmitted from the hub outdoor device (HOU) 30 is demodulated.

The hub outdoor unit (HOU) 30 amplifies and frequency-converts downlink channel data transmitted from the head-end unit 20 and transmits it to the subscriber side through the high-directional antenna, The data received through the wireless section is amplified and frequency-converted and transmitted to the head-end unit 20.

In addition, the subscriber unit (CPE) 40 includes a customer outdoor unit (CPE ODU) 41 installed outdoors, and a network interface unit (NIU) 42 installed indoors. And peripheral devices such as a telephone 43, a personal computer 44, a set-top box (STB) 45, and a television 46 for other application services.

Here, the subscriber unit (CPE) 40 is configured of the network interface unit (NIU) 42 and other peripheral devices (43, 44, 45, 46) depending on whether the LMDS system for home use or office use. The configuration will be different.

In other words, if the LMDS system is used for the office, the North American / European Transmission Interface (T1 / E1 Interface) is provided so that only a small capacity Private Automatic Branch Exchange can be used, and many local area network services (LAN) are desired. A local area network server (LAN Server) for client (Client) is provided, where Ethernet (Ethernet) can be used through a local area network server (LAN Server).

In the subscriber device (CPE) 40, the subscriber outdoor device (CPE ODU) 41 converts and amplifies data input through the high-directional antenna to the network interface device (NIU) 42, Alternatively, the data transmitted to the network interface device (NIU) 42 is frequency-converted and amplified and transmitted to the radio section through the high-directional antenna.

The network interface device (NIU) 42 interfaces with the subscriber outdoor device (CPE ODU) 41 and the peripheral devices 43, 44, 45, and 46, which are a plurality of data terminals.

2 is a diagram illustrating a structure of an uplink timeslot according to the prior art.

Referring to FIG. 2, the time slot structure of the uplink channel shown in accordance with the DAVIC recommendation is that the subscriber equipment (CPE) 40 shown in FIG. 1 is upstream data to the head-end unit 20. This is a structure of timeslots that can be used to transmit.

The uplink timeslot includes one polling timeslot 50, two guard timeslots 51, eleven contention time slots 5, and 130 reserved time slots ( 53).

The time slots that can be transmitted upward by the network interface device (NIU) 42 among the uplink time slots are the polling time slot 50, the contention time slot 52, and the reservation time slot 53.

In this case, the polling timeslot 50 includes a subscriber device (CPE) 40 when the head-end unit 20 polls all the subscriber device (CPE) 40 at a predetermined time. Is the time slot to send the response. The polling timeslot 50 is located first in the uplink timeslots.

The contention timeslot 52 is a MAC message or signal such that a subscriber device (CPE) 40 is a head-end unit 20, such as a reservation channel request and channel release, rather than general user data. It is used to send a signaling message.

According to the DAVIC recommendation, the contention timeslot 52 may not only use a particular network interface unit (NIU) 42 but also several other network interface units (NIUs) 42 that may be used at the same time.

After transmitting the data, the network interface device (NIU) 42 analyzes the next downstream frame to determine whether there is a collision of transmission data.

Here, if a collision occurs, a random delay method that waits for retransmission and then retransmits is used.

The reservation timeslot 53 is used by a user to transmit data such as voice or Internet data. The reservation timeslot 53 allows a subscriber device (CPE) 40 to request a reservation channel request message as a contention time slot 52. When the transmitter transmits and receives an acknowledgment message for the request message from the head-end unit 20, it becomes available.

As such, the upward time slot structure according to the DAVIC recommendation is a fixed time slot that fixes the position and number of each time slot and is not actively changed by any variable during operation.

In the operation of the uptime timeslot, which is a fixed timeslot according to the DAVIC Recommendation, when transmitting upstream data from the subscriber device (CPE) 40, the control signal is transmitted via the contention timeslot 52, and the user data is reserved time. Slot 53 is used.

In case of applying the uptime timeslot according to the DAVIC recommendation to internet service which is data communication, the following problem occurs.

If the LMDS system provides an Internet service, general subscribers will use the LMDS system a lot for receiving some information from the Internet called sea of information rather than sending data to a web server. That is, there is more data going from the network side to the subscriber device (CPE) and less data going from the subscriber device (CPE) to the network side.

In addition, the user does not transmit the upstream data while searching for the received information, and performs a procedure of completing the search for the received information and requesting the desired information again.

Therefore, data sent upstream is sometimes generated nonflammable.

When the LMDS system uses the fixed time slot structure uplink time slot in providing the Internet service, the LMDS system continuously occupies the uplink time slot or requests a reserved time slot when there is data to be sent and then allocates and uses it.

However, most of the data transmitted upstream is short data of tens to hundreds of bytes.

In order to send such short data, it is necessary to continuously occupy an uptime time slot or request a reserved time slot, transmit data after receiving an allocated time slot, and perform various operations such as releasing a used time slot. ) To increase traffic and cause transmission delay.

Therefore, when the LMDS system provides a multimedia service, it is impossible to proactively cope with traffic changes, and it is difficult to expect improved channel efficiency.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is an adaptive time slot capable of actively coping with traffic changes when the LMDS system provides a multimedia service, thereby improving channel efficiency. It is to provide a channel efficiency improvement method using the method.

According to a feature of the present invention for achieving the above object, in the method for improving channel efficiency using the adaptive timeslot method, the uplink timeslots are transmitted every time, in the transmission of voice and data from the plurality of subscriber devices to the system. When polling a subscriber device, a polling time slot to which the subscriber device sends a response, a guard time slot to prevent the signal through the polling time slot from interfering with other timeslots when out of sync, and the subscriber device is a headend device. A competition time slot for sending control data to the mobile station; a reservation time slot for sending user data; and an adaptive time slot including a portion of the competition time slot and a portion of the reservation time slot. Add the number of slots allocated for the competition time slot and the reserved time slot for data transmission. It will ever operate.

Advantageously, some of the reserved time slots for the user data transmission are operated as dedicated timeslots for specific subscribers that transmit data over a dedicated line.

In addition, the number of slots to be used is determined according to the number of subscribers whose services are used to transmit the control data through the system and the type of service used by the subscribers. When transmitting, the subscribers are assigned an order of transmitting the user data or a probability value that can be transmitted.

In addition, the competitive timeslot of the adaptive timeslot is used to transmit some user data for a data communication service, and the reserved timeslot of the adaptive timeslot includes some user data for a data communication service and voice for a voice service. Used to transmit

In the feature according to the present invention, the data and voice transmission using the reserved timeslot of the adaptive timeslot transmits a message to the system requesting allocation of the reserved timeslot through a contention timeslot for transmitting the control data. And determining whether to allocate the requested reservation timeslot by analyzing the transmitted allocation request message, and receiving, by the subscriber device, a timeslot assignment message according to the verification result and allocating the data and voice. Transmitting via the reserved reservation time slot.

Here, when the data or voice transmission is completed after the step of transmitting the data and voice, a message for releasing the allocated timeslot is transmitted to the system, and the request message in the step of transmitting the allocation request message. Contains the amount of data to be transferred and the number of timeslots to use.

In addition, the step of checking whether the allocation is performed or not checks whether there is a time slot allowance through an upstream management table provided in the system, and confirms whether to allocate the requested reservation timeslot.

1 is a block diagram showing a part of a typical LMDS system.

2 is a diagram illustrating a structure of an uplink timeslot according to the prior art.

3 is a diagram illustrating a structure of an upward timeslot according to the present invention.

4 illustrates an example of using an adaptive timeslot in accordance with the present invention.

Fig. 5 is a block diagram showing the configuration of a radio management unit of a head-end unit.

6 is a diagram illustrating a reserved data slot table in an uplink slot management table of a wireless manager;

* Description of the symbols for the main parts of the drawings *

10: Central Office Unit (COU) 20: Head-end Unit

30: hub outdoor unit (HOU) 40: subscriber unit (CPE)

62: competition timeslot 63: adaptive timeslot

64: dedicated time slot 80: wireless management unit

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

The LMDS system is a system that can provide various multimedia services such as voice, video, and data to subscribers in both directions.

When the LMDS system performs the voice service through the PSTN, the subscriber device (CPE) occupies one uplink channel from the start of the call to the end to transmit voice. This takes longer time to occupy upstream channels than other services.

When serving a video such as Video On Demand, the subscriber device (CPE) has a very small amount of data sent upwards. Furthermore, while viewing the program, it rarely transmits upstream data.

In the case of data communication such as the Internet, a subscriber station (CPE) transmits more upstream data than a video on demand service (VOD) and less upstream data than a voice service through a PSTN.

If LMDS system provides multimedia service, Internet service is expected to be the most important. This is because voice communication through PSTN is already installed, and VOD is not activated yet.

The present invention intends to propose a time slot structure of an uplink channel suitable for more effectively providing data communication among such multimedia services.

3 is a diagram illustrating a structure of an uplink timeslot according to the present invention.

Referring to FIG. 3, in the present invention, a polling time slot 60, a guard time slot 61, a contention time slot 62, and an adaptive time slot (ATS) 63 as an uplink time slot. And a dedicated time slot (DTS) 64.

The polling timeslot 60 is a timeslot located at the beginning of timeslots of the upframe.

In this way, the polling timeslot 60 is positioned at the beginning of an upframe because the uplink and downframe periods are the same in the LMDS system, so that the uplink data is not synchronized with the subscriber device (CPE) 40 yet. This is because it is easy to send the start of a frame when sending a.

Next to the polling timeslot 60 is a guard timeslot 61 to prevent the signal through the polling timeslots from interfering with other timeslots in the out of synch state.

The number of these guard timeslots 61 is determined by a round trip delay between the head-end unit 20 and the subscriber device (CPE) 40. This means that the longer the round trip delay, the greater the number of guard timeslots 61.

The contention timeslot 62 is located after the protection timeslot 61.

The contention timeslot 62 is a time slot used by the subscriber device (CPE) 40 to send control data to the head-end unit 20, which is shared by several subscriber devices (CPE). This can cause a crash.

The number of these contention timeslots 62 is determined by the number of subscribers receiving services from the head-end unit 20 and the type of service they use.

Except for these polling timeslots 60, guard timeslots 61, and competing timeslots 62, all timeslots are timeslots for sending user data.

The adaptive timeslot (ATS) 63 is a time slot for sending data and voice, and the dedicated timeslot (DTS) 64 is a time slot used for leased lines. Send the data of (T1 / E1).

The competitive data slot of the adaptive timeslot (ATS) 63 is a slot for sending short data in data communication.

For example, in the case of internet communication, most of the data sent to the network by the subscriber are data corresponding to clicking with the mouse or inputting from the keyboard. These data are sent directly to the competing data slots without using the reserved data slots of the adaptive timeslot (ATS) 63 because the messages are short.

This reduces the transmission delay time than requiring and allocating a reserved data slot when sending short data, and is more efficient in terms of resource management of the head-end unit 20.

However, since a contention data slot is a slot shared by several subscribers, collision may occur like the contention time slot 62.

In order to solve such a slot collision problem, each subscriber device (CPE) 40 is assigned an order to transmit data or a probability value is transmitted.

The reserved data slot of the adaptive timeslot (ATS) 63 is a slot for sending voice or long data through the PSTN.

In order for the subscriber device (CPE) 40 to use the reservation data slot of the adaptive timeslot (ATS) 63, it first reserves data to the head-end unit 20 using the contention timeslot 62. A slot request message should be sent and a specific reserved data slot should be allocated and used in response.

Hereinafter, one embodiment of a channel efficiency improvement method using an adaptive timeslot method according to the present invention will be described.

4 is a diagram illustrating an example of using an adaptive timeslot according to the present invention.

In FIG. 4, subscriber A 75 sends long data such as an e-mail or a file, and subscriber B 76 sends short data corresponding to a mouse click or a keyboard input. It is seen.

Referring to the case of transmitting long data, subscriber A 75 transmits data using a reserved data slot of adaptive time slot (ATS) 73.

In this case, a message requesting a reserved data slot is first transmitted to the head-end unit 20 through the contention timeslot 72, and the request message is sent with the amount of data to be transmitted and the number of timeslots to be used. (S1).

The number of timeslots required by subscriber A 75 is less than or equal to the number of reserved data slots.

FIG. 5 is a block diagram showing the configuration of a radio management unit of a head-end unit. The reservation data slot request message transmitted from subscriber A 75 through the contention timeslot 72 is shown in FIG. This radio management unit 80 of the head-end unit 20 receives.

In the radio manager 80, the receiver 81 receives the request message of the subscriber A 75 and provides it to the MAC processor 83.

The central processing unit 85 analyzes the request message provided from the MAC processing unit 83 and checks whether the subscriber A 75 can allocate as many reserved data slots as requested through the request message. Search for 84).

The reserved data slot table in this uplink slot management table 84 is shown in FIG.

In the illustrated reserved data slot table, a state in which a slot is currently allocated and in use is represented by "0x0f", and a state not in use is represented by "0".

If the subscriber A 75 has requested one reserved data slot, the slot number " k + 5 " is allocated in the reserved data slot table.

At this time, the central processing unit 85 of the wireless management unit 80 indicates that the slot number "k + 5" of the reservation data slot table is assigned by writing "0x0f".

Subscriber A 75 receives a time slot assignment message for allocating a reserved data slot from the wireless management unit 80 of the head-end unit 20 (S2), and allocates the reserved reserved data slot (k +). 5) it transmits the long data it wants to send (S3).

When the subscriber A 75 completes all data transmission, the time slot release message is transmitted to the wireless management unit 80 of the head end unit 20 (S3), and the long data transmission process of the subscriber side is terminated. .

The head_end unit 20 receives the time slot release message from the subscriber A 75 and transmits a response thereto to the subscriber A 75 (S2), and at the same time, the subscriber A just received the reservation data slot table. "0" is written in the slot number "k + 5" used by (75) instead of "0x0f" to indicate that it is not in use.

When subscriber B 76 communicates with the Internet, if subscriber B 76 wants to transmit short data corresponding to a mouse click or a keyboard input, most of the data sent to subscriber network 76 is subscriber B 76. In the adaptive timeslot (ATS) 73, data is directly transmitted using a contention data slot without using a reserved data slot (S4).

At this time, if a collision occurs while transmitting short data to a contention data slot, it waits for some time and retransmits using a random delay method of transmitting data again.

Subscriber B 76 transmits the short data through the competing data slot of Adaptive Timeslot (ATS) 73, so that it does not have to go through a complicated process like Subscriber A 75. Therefore, the data transmission delay time is reduced and the time slot allocation process by the message exchange with the wireless management unit of the head-end unit 20 is not performed. The load can be reduced.

When the LMDS system provides various multimedia services, service requests of subscribers are not constant. In other words, there may be many or fewer subscribers requesting services over time. In addition, there is only one service that you want to use, but you can use it frequently and use various services.

Therefore, in this situation, the traffic is not constant and constantly changes.

The adaptive timeslot (ATS) 73 adjusts the ratio of contention data slots and reserved data slots to proactively cope with the situation where traffic suddenly changes in a situation where the traffic is not constant.

If there is an increase in the number of subscribers using Internet services in the LMDS system to increase contention for contention data slots, the number of contention data slots in the adaptive timeslot (ATS) 73 is increased. In the adaptive timeslot (ATS) 73, the number of reserved data slots is reduced by the increased number of contention data slots.

Conversely, if the number of users using voice services over the PSTN in the LMDS system increases or the usage rate of the competing data slots decreases, the number of reserved data slots in the adaptive timeslot (ATS) 73 is increased. In the adaptive timeslot (ATS) 73, the number of contention data slots is reduced by the number of reserved data slots.

In the channel efficiency improvement method using the adaptive timeslot method of the present invention described above, the adaptive timeslot (ATS) 73 can be used to flexibly cope with the rapidly changing traffic.

As described above, the present invention applies an adaptive timeslot that is actively operated according to traffic in an LMDS system that provides various multimedia services, and thus, it is possible to flexibly cope with rapidly changing traffic.

In addition, when LMDS system provides wireless data service such as the Internet, it actively allocates time slots used to transmit general user data, thus accommodating more subscribers and also providing a head-end unit. ) Can reduce upstream data throughput.

Claims (9)

In transmitting voice and data from multiple subscriber devices to the system, the uptime timeslot is A polling time slot to which the subscriber device sends a response when polling all subscriber devices at a given time; A guard time slot to prevent a signal through the polling time slots from interfering with other timeslots in synchronization; A competition time slot in which the subscriber device sends control data to the headend device; A reservation time slot for sending user data; An adaptive time slot comprising a portion of the competition time slot and a portion of the reserved time slot, The adaptive timeslot is a channel efficiency improvement method using an adaptive timeslot method, characterized in that the number of slots allocated to the contention time slot and the reserved time slot for the user data transmission in accordance with traffic conditions. The method of claim 1, wherein some of the reserved time slots for the user data transmission are operated as dedicated time slots for a specific subscriber that transmits data through a dedicated line. How to improve channel efficiency. 2. The adaptive timeslot as claimed in claim 1, wherein the contention timeslot used to transmit the control data is determined by the number of subscribers provided with the service and the number of slots used by the subscribers. How to improve channel efficiency using the scheme. The channel using the adaptive timeslot method according to claim 1, wherein when transmitting the user data through the contention timeslot, a sequence of transmitting the user data is provided to each subscriber or a probability value that can be transmitted is provided. How to improve efficiency. 2. The method of claim 1, wherein the contention time slot of the adaptive timeslot is used to transmit some user data for a data communication service, and the user time data portion of the adaptive timeslot is part of the reserved timeslot. And a method for improving channel efficiency using an adaptive timeslot scheme, characterized in that it is used to transmit voice for voice service. The method of claim 1, wherein the data and voice transmission using the reserved timeslot of the adaptive timeslot, Sending a message to the system requesting the reservation timeslot allocation via a contention timeslot for transmitting the control data; Analyzing the transmitted allocation request message to determine whether to allocate the requested reservation timeslot; And receiving, by the subscriber device, a timeslot assignment message according to the verification result, and transmitting the data and voice through an allocated reserved timeslot. 7. The method of claim 6, wherein after transmitting the data and voice, if the transmission of the data or voice is completed, a message for releasing the allocated time slot is transmitted to the system. How to improve channel efficiency. 7. The method of claim 6, wherein in the step of transmitting the allocation request message, the request message includes an amount of data to be transmitted and a number of timeslots to be used. 7. The adaptive time determining method according to claim 6, wherein the step of confirming whether to allocate the information or not comprises: searching for the presence or absence of a time slot margin through an upstream management table provided in the system, and confirming whether to allocate the requested reservation time slot. Channel efficiency improvement method using slot method.